Evaluating a long, closed and inaccessible structure of machines or an internal hollow viscus of a living body without surgical methods has been greatly improved by development of flexible endoscopic apparatus that can be inserted into the closed structure of the machine or the hollow viscus under direct visual guidance. For evaluation of human body, it allows critical visual inspection of inner structure of the hollow viscus and guided procedures such as obtaining tissue samples and surgical procedures using insertable instruments. Endoscopic procedures now have become an essential component of evaluation and treatment of diverse pathologies of the hollow viscus of the body. For an example, inspection of colon by a colonoscope is universally required as a screening tool for early detection of colon cancer in the Western countries. Similarly, gastroduodenoscope is being used for screening stomach cancer in Asian countries.
Endoscopic apparatus in general comprises a distal end that is bendable by internal guide-wires, a proximal end that controls the distal end by the guide-wires and a tubular shaft that houses internal conduits and connects both ends. Image of a target area is acquiesced electronically by an image sensor that is attached to an optic lens complex of the distal end and is connected to the proximal end and a power and control unit via longitudinally linear electric cables. The optic lens complex at the distal end is cleansed by water for clear view of a target area. Gas such as air is insufflated to the target area for three dimensional expansion of the area and negative suction is applied to the target area to remove unwanted fluids and gas. Water, gas and negative suction are provided through longitudinally linear tubular conduits connected to the distal end. Instrumentation of devices such as biopsy forceps is done through a linear tubular channel that runs from a hub located at the proximal end to the distal end.
Bending of a tubular shaft of an endoscope usually is achieved by linear pull-strings that run longitudinally inside the tubular wall from control knobs of the proximal end to internal bending anchors of the distal end. There is no active bending action outside the bendable segment of the distal end. The tubular shaft between the bendable segment and the proximal end usually is flexible to a certain degree, allowing it to passively curve inside the tubular structure. Forward movement of the distal end of an endoscope usually is achieved by manually pushing the proximal end into the tubular structure.
The aforementioned endoscope accordingly has a structure of a hollow tube of a fixed length in which a number of hollow tubular conduits and channels of a similarly fixed length are longitudinally placed, between the two opposite ends. Main advantages of said endoscope include real-time maneuverability, its access to target tissues of the majority of the tubular structure of a living body and most importantly its capability to obtain biologic samples and to manipulate the target area under direct vision. Main disadvantages of said endoscope come from its inability to navigate in a meandering tubular structure such as a zigzagging small intestine and its fixed length beyond which no further evaluation could be achieved. Capsular endoscopic instruments are developed to circumvent the need to navigate in the zigzagging small intestine without length limitation. These devices can be swallowed and be let tumble down through the tortuous small intestine, while acquiescing digital visual information of said intestine. One most significant drawback of said capsular endoscopes, however, is the most critical, which is their inability to obtain a sufficient amount of biologic samples and to manipulate the target area. As a result, capsular endoscopes usually are used for screening purpose. If abnormalities are found in the deep part of said small intestine that cannot be reached by existing tubular endoscopes, further evaluation and therapy may only be achievable through direct surgery.
Difficulties in forward movement of a distal end of an endoscope in said zigzagging small intestine come from its dependence on passive forward push from the proximal end and presence of opposite directions of segments of the small intestine in contrast to a large intestine that can be considered as one continuous arc that can be reached by one direction of forward movement. Bending of a bendable part of the distal end alone may not allow passage of a tubular shaft of the endoscope through the zigzagging small intestine since the tubular shaft usually has a fixed directional flexibility that may not be changed simultaneously at points of opposite direction. These technical challenges may be offset by devices that control flexibility of the shaft while generating active forward movement at the site of changes in direction. Generating forward zigzagging movement of said shaft along a contour of the meandering small intestine could further enhance navigation of said tubular device toward a target area in an otherwise inaccessible location.
Controllable flexibility at a site of forward movement of a segment of a tubular shaft may be achievable if the segment of the shaft is made longitudinally extend or contract and made bend by pressure changes inside the segment. A medium such as gas or liquid including gaseous phase of liquid is delivered into the segments of the tubular shaft by a power and control unit. The medium occupies an inner space in the tubular shaft of the endoscope and/or can be localized in predefined longitudinal spaces along the tubular shaft. Volume and pressure of the medium can be changed by the power and control unit and said changes in the volume and pressure translate into changes in length of the segments and generate differences in outward radial tension on walls of the segments of the shaft.
One other technical challenge in a tubular shaft that controllably varies in length is that channels and conduits inside the tubular shaft should be made vary in length together with changes in length of the tubular shaft. Electric cables for the electronic image sensor and other components can be coiled telephone-cord-like inside the tubular shaft, which extends by longitudinal stretching. Internal conduits for water, gas and suction may also be made in a similar way, which may all be consolidated with the electric cables in one telephone-cord-like coil. The telephone-cord-like coil then connects the power and control unit to the distal end, with its pitches and diameter of the coil dependent on a ratio of straightened state to coiled state and on an internal diameter of the tubular shaft. Internal channel for instruments, however, requires longitudinally straight configuration from the proximal end to the distal end to allow passage of instruments without mechanical hindrance. Longitudinally linear bellows-shaped construction of the channel may accomplish the goal, which contracts and extends along the longitudinal axis of the channel.
Forward axial movement of the distal end may best be achieved by longitudinal extension of segments of a tubular shaft located proximal to the distal end. Ideally, segments of the shaft may be extended sequentially, starting from the most proximal segment to the most distal segment that is attached to the distal end. Sequential segmental extension may accommodate differences in linear length of an intestine in between of two opposite curves of the intestine, in radii of curves of the intestine and in direction of the curves.